Package dev.frostlake.functions.window

Class WindowFunctionArity

java.lang.Object
dev.frostlake.functions.window.WindowFunctionArity
public final class WindowFunctionArity extends Object
How many arguments each window function takes, and live's two sentences for a call that gets it wrong. Every bound here is live-measured: 
   ROW_NUMBER RANK DENSE_RANK PERCENT_RANK CUME_DIST   0        RANK(a) is "expected 0, got 1"
   LEAD LAG                                            1 to 3   LAG(a,1,0) runs; a fourth is refused
   NTILE FIRST_VALUE LAST_VALUE                        1
   CONDITIONAL_TRUE_EVENT CONDITIONAL_CHANGE_EVENT     1
   NTH_VALUE                                           2        NTH_VALUE(a) is "expected 2, got 1"

★ THE TWO SENTENCES ARE PUNCTUATED DIFFERENTLY, which is measured rather than tidied: the too-few one carries a comma after the bracket and the too-many one does not.

★ ARITY OUTRANKS EVERYTHING ELSE ABOUT THE CALL. LEAD() is refused for its argument count whether or not it carries an OVER clause — the missing specification is never reached — and the refusal is POSITIONED on the call itself, where the missing-specification sentence carries no position at all.

★ WHAT IS DELIBERATELY ABSENT: RATIO_TO_REPORT, whose refusal live words in SUM's name rather than its own, and the dual-role aggregates (SUM, COUNT, AVG, MIN, MAX), which are answerable with no window at all and carry an aggregate's arity rules instead.

  • Method Details

    • isMeasured

      public static boolean isMeasured(String name)
      Whether this name's argument count is one we know how to judge.

    • refusal

      public static String refusal(String name, String echo, int given)
      Live's refusal for a call of the wrong arity, or null when the count is legal.
      Parameters:
      name - the upper-cased function name
      echo - the call as the plan prints it, brackets excluded
      given - how many arguments were written
      Returns:
      the refusal detail, or null